ANTIGENIC STRUCTURE OF THE OONOCOOCUS 545 



became covered with papillae ; Type II gave a smaller, round, low convex or raised, 

 yellowish- white, opaque colony, with a slightly uneven surface, and an entire or 

 faintly lobate edge ; no papillae were formed. Serologically, colonies of Type I 

 could be differentiated from those of Type II. Atkin foimd that the organisms 

 in the papillae of Type I colonies lived about twice as long as did those in the 

 flat part ; he therefore concludes that the papillae arise as a reaction to an un- 

 favourable environment, and represent the first step in the change over to Type II. 

 In some colonies the papillae actually fuse together, so that they constitute the 

 entire colony ; the papillated appearance is thus lost. During the course of 

 subculture in the laboratory, there will be a constant selection of the longer-living 

 organisms in the papillae, so that eventually the strain will consist entirely of 

 these organisms ; when this process is complete, the strain will belong culturally, 

 and probably serologically, to Type II. Type I colonies are usually observed 

 when pus from acute gonorrhoaa is plated out ; Type II colonies are usually found 

 in old laboratory cultures, or occasionally in chronic gonorrhoaal lesions. 



Atkin would regard Type I as being highly parasitic, and Type II as a more 

 saprophytic form of the gonococcus. Though he obtained evidence that, in the 

 laboratory, Type I strains gradually acquired the properties of Type II strains, he 

 was never able to follow the complete transition ; probably this is a matter of 

 months or years. It must not be supposed that gonococci can in practice be 

 divided sharply into two colonial types ; between the two main types there are 

 probably numerous sub-types, each representing one stage in the process of trans- 

 ition. This accounts for the numerous arbitrary subdivisions that have been 

 made on serological grounds by different workers (see below). But, broadly speak- 

 ing, there appear to be two main centres around which the different strains may be 

 grouped ; the type strains can be differentiated both by colonial form and serological 

 behaviour. In these respects the gonococcus closely resembles the meningococcus. 



Antigenic Structure. — Agglutination. — The serological study of the gonococci may 

 be said to have commenced with Bruckner and Cristeanu's work in 1906 (1906a). Using 

 immune horse serum prepared by the injection of pure cultures of different strains, they 

 found that the gonococci were agglutinated to a titre of about 1-750. A close relationship 

 was estabUshed between the gonococcus and the meningococcus, both of which were 

 agglutmated to nearly equal titre by a gonococcal serum (Bruckner and Cristeanu 19066). 

 Vanned in the same year (1906) found that immune gonococcal rabbit serum contained 

 agglutinins for the gonococcus and to a less extent for the meningococcus. Torrey (1907) 

 was the first to use the agglutination test for the serological differentiation of the gonococci. 

 Working with 10 different strains and 8 immune sera, he found that there was a difference 

 in the agglutinabiUty of the gonococci ; and in conjunction with the absorption of agglu- 

 tinins test he was able to divide the 10 strains into 3 groups. Such a differentiation was 

 obviously of interest, but many subsequent workers failed to confirm this (Wollstein 

 1907, Vanned 1907, Thomsen and VoUmond 1921, Cook and Stafford 1921, Warren 1921). 

 More recent work has, however, tended to show the essential correctness of Torrey' s findings. 

 Thus Pearce (1915) drew a distinction on the basis of direct agglutination between strains 

 of gonococci isolated from infants — vulvovaginitis and ophthalmia — and those isolated 

 from adults — acute urethritis. Hermanies (1921a) studied 85 strains, and using the 

 absorption of agglutinins test he was able to classify them into 6 types, of which Types I 

 and II contained the greatest numbers. Later (19216) he subdivided his Type II strains 

 into 4 races, a, 6, c, and d. He found a considerable amount of lability in the antigenic 

 structure of these races ; some were simple, while others were more complex. Jotten 

 (1921), by direct agglutination, classified 20 out of 27 strains into 4 groups, A, B, C, and 

 D ; 7 remained ungrouped. The strains falling into Groups A and B were mostly from 

 P.B. T 



